The present invention relates to a charged particle detector, or a charged beam processing of performing reactive etching, beam assisted deposition and the like using a charged beam and process gases, and more particularly to a method of processing a sample using a charged beam and reactive gases and a system employing the same.
In recent years, in a semiconductor device such as LSI, in order to promote high integration and high functionality, the wiring and the elements have been advanced in multi-layer structure. Therefore, for the purpose of performing the debugging of the LSI design and the failure analysis in the manufacturing process, the request of cutting the wiring on a chip or connecting arbitrary parts to each other to perform the circuit modification for a short time has increased rapidly. For such circuit modification, it is necessary to perform the processing over several tens of positions on one LSI, and therefore the processing must be performed at high speed and at a high yield near 100%.
Out of the above-mentioned methods, as for the method of cutting the wiring, the sputtering processing method has heretofore been employed in which the atoms contained in the wiring material are sputtered by the focused ion beam. In this method, however, there arised serious problems that the processing speed is too slow, the selectivity is small for the material of a workpiece, and the sputtered atoms are deposited to the side face of the workpiece.
On the other hand, if the chemical reactive etching is used in which the reactive gases and the charged beam such as the focused ion beam or the electron beam, the processing can be performed at high speed several tens of times as rapid as the sputtering processing, and the selectivity for a layer under the layer to be processed can be increased by selecting the kind of reactive gas. In addition, it is possible to perform the processing with accuracy by which even for the sample having remarkable irregulation, the lower layer is not damaged.
However, in the case of the chemical reactive etching method, when the reactive gases are introduced, a charged particle detector for detecting an image is exposed to the reactive gases by the diffusion of the reactive gases, so that an active surface of the charged particle detector is corroded. As a result, there arised a problem that the performance of the secondary particle detector is readily degraded, and thus the charged particle detector must be exchanged frequently.
Then, there is well known JP-A-3-245529, as the prior art, in which in order to solve the above-mentioned problem, a shutter mechanism is provided in the front of a secondary electron amplification unit of the charged particle detector.
In the above-mentioned prior art, in the case where after the desired processing has been performed using the reactive gases and before a main chamber is not sufficiently exhausted, the shutter mechanism provided in the front of the secondary electron amplification unit of the charged particle detector is opened, the remaining reactive gases enter into the charged particle detector. Then, if the shutter mechanism is shut in order to perform the processing again with the processing state left as it is, the reactive gases will be shut in the charged particle detector. Therefore, it is impossible to prevent the performance of the charged particle detector from being degraded. Moreover, by repeating the opening and shutting of the shutter mechanism, likewise, the reactive gases will remain in the charged particle detector. Therefore, the problem of the degradation of the performance can not be avoided. In addition, in the case where even if this shutter mechanism is provided, the process gases can not be necessarily, perfectly intercepted due to the limitation in construction, the process gases leak through a small gap to enter into the detector, and as a result, there is the possibility that the performance is degraded due to the corrosion.